Old Reservoir is a 21-acre productive, nutrient-rich eutrophic lake in Randolph County, Missouri. Water quality is graded C based on 3 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 6 other monitored lakes in Randolph County, Old Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-17. Grade methodology: LakeGrade methodology.
Watch Old Reservoir water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Murky, only visible to about 3.6 ft. Phosphorus level: 33 µg/L. Chlorophyll-a: 14.2 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.6 ft | D |
| Phosphorus | 33 µg/L | C |
| Chlorophyll-a (Algae) | 14.2 µg/L | C |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 21 acres |
| Public Access | Yes |
Where to stay near Old Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Old Reservoir in Randolph County, Missouri — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Old Reservoir
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Old Reservoir?
Get lake water-quality report cards plus the best cabin & lodging deals near Old Reservoir — straight to your inbox. No spam, unsubscribe anytime.
Planning a whole trip? See where to stay at Missouri’s top lakes →
Fishing Old Reservoir
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.226 m/yr | 5 |
| Phosphorus | ↑ Improving | -4.33 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -3.81 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Old Reservoir averages about 80°F at the surface in summer, usually warmest in Jul (about 82°F) and coldest in Apr (about 59°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 98 field readings (2010–2024) via the EPA Water Quality Portal. See the full Old Reservoir water temperature breakdown →
Location
County Ranking
Ranked #1 of 7 lakes in Randolph County
Nearby Lakes in Randolph County
Explore Old Reservoir across LakeGrade
More Missouri Lake Rankings
Other Grade C Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
Reservoir Info (USACE NID)
Old Reservoir is a man-made reservoir impounded by the Water Works Lake Dam (completed 1870), built primarily for recreation on the TRIBUTARY TO SWEET SPRING CRK; earth-type dam, 30 ft tall.
- Surface area
- 21 ac
- Normal storage
- 147 ac-ft
- Max storage
- 337 ac-ft
- Drainage area
- 418 sq mi
- Hazard class
- High
- Owner
- MOBERLY-PARKS&RECREATION
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID MO10006 · Operator website · Matched by proximity (0.04 km)
Regulated Pollution Sources Nearby
4 EPA-permitted facilities operate within about 5 miles of Old Reservoir under Clean Water Act (NPDES) discharge permits. 4 facilities have a reported Clean Water Act violation in the past three years.
- Fox Hollow Wastewater Treatment FacilityMoberly · 1.2 mi away · NPDES MO0035599Recent violation
- Orton Lane WwtfMoberly · 1.7 mi away · NPDES MO0121622Recent violation
- Heritage Hills Golf Course WwtfMoberly · 2 mi away · NPDES MO0095605Recent violation
- Moberly Mo Llc WwtfMoberly · 3.1 mi away · NPDES MO0045021Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-09-17
Monitoring stations: 1